GPLize project

Finally deciding to move things into a proper license; which I can do
since I've never accepted (or had :( ) a pull request from another
person

1 files changed, 123 insertions, 0 deletions

diff --git a/src/main/java/bjc/esodata/KeyedList.java b/src/main/java/bjc/esodata/KeyedList.java
new file mode 100644
index 0000000..5b0d6cc
--- /dev/null
+++ b/src/main/java/bjc/esodata/KeyedList.java
@@ -0,0 +1,123 @@
+/* 
+ * esodata - data structures and other things, of varying utility
+ * Copyright 2022, Ben Culkin
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *   
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package bjc.esodata;
+
+import java.util.*;
+
+public class KeyedList<Key, Val> implements Iterable<Val> {
+	private List<Val> backing;
+	private Map<Key, Integer> indices;
+
+	private int currIdx = 0;
+
+	public KeyedList() {
+		backing = new ArrayList<>();
+		indices = new HashMap<>();
+	}
+
+	/**
+	 * Add a item to this list.
+	 * 
+	 * If an item already exists with the given key, the current one will not be
+	 * added. Use <code>set</code> to handle that.
+	 * 
+	 * @param key The key for this item.
+	 * @param val The value for this item
+	 * 
+	 * @return Whether or not this item was added to the list
+	 */
+	public boolean add(Key key, Val val) {
+		// TODO: Determine if this is the desired behavior
+		if (indices.containsKey(key))
+			return false;
+
+		backing.add(val);
+		indices.put(key, currIdx++);
+		return true;
+	}
+
+	/**
+	 * Set the item associated with a given key.
+	 * 
+	 * @param key    The key to set
+	 * @param newVal The new value for the key
+	 * 
+	 * @return The previous value for the key, if there was one
+	 */
+	public Val set(Key key, Val newVal) {
+		if (indices.containsKey(key)) {
+			return backing.set(indices.get(key), newVal);
+		}
+
+		add(key, newVal);
+		return null;
+	}
+
+	/**
+	 * Retrieve all of the keys for this list.
+	 * 
+	 * @return An immutable set of the keys for this list
+	 */
+	public Set<Key> keys() {
+		// TODO: write mutable wrapper which will update the list appropriately
+		return Collections.unmodifiableSet(indices.keySet());
+	}
+
+	/**
+	 * Retrieve the value associated with the given key.
+	 * 
+	 * @param key The key to look up.
+	 * 
+	 * @return The value for the given key.
+	 */
+	public Val get(Key key) {
+		return backing.get(indices.get(key));
+	}
+
+	/**
+	 * Check if this list contains a value for a given key.
+	 * 
+	 * @param key The key to look up.
+	 * 
+	 * @return Whether this list contains a value for the given key.
+	 */
+	public boolean containsKey(Key key) {
+		return indices.containsKey(key);
+	}
+
+	@Override
+	public Iterator<Val> iterator() {
+		return backing.iterator();
+	}
+
+	/**
+	 * Return an iterator that starts at the value for the given key.'
+	 * 
+	 * @param key The key to start at.
+	 * 
+	 * @return An iterator starting at the given key, or null if the key isn't
+	 *         present.
+	 */
+	public ListIterator<Val> iteratorFrom(Key key) {
+		if (indices.containsKey(key)) {
+			return backing.listIterator(indices.get(key));
+		}
+
+		return null;
+	}
+}